Europe was supposed to set Rafael Benítez apart but at present it is merely adding to his angst. Chelsea were beaten again here and must now turn over a deficit in next week's return leg in London if they are to force passage beyond Steaua Bucharest into the quarter-finals of the Europa League. Recovery is not beyond them in the tie but, with a wounded Manchester United to come on Sunday and their own confidence bruised, a pervading sense of anxiety persists.

Nothing has been simple about this traumatic season, so perhaps this latest setback was partly to be expected. The reigning European champions rarely imposed themselves on an occasion that cried out for dynamism, their urgency reserved for the period just after they had conceded the game's only goal and then, later, as Steaua retreated in on themselves. Benítez pointed to the excellence of the home goalkeeper, Ciprian Tatarusanu, as evidence of dominance but, in truth, this was never impressive.

Rather Chelsea can appear jaded when games are drifting and the onus is on them to inject pace and creativity into a contest. They looked sluggish for periods, perhaps grateful that Steaua had not torn into them from the outset, but their own head of steam was belated and rather fitful. Tatarusanu denied the substitute Marko Marin at his near post, the German having been found wonderfully by John Terry's raking pass to the far side. But that, seven minutes from time, was as close as they came as they chased an equaliser late on. This was the 50th game of a slog of a season that has been accompanied by too many disappointments already. It felt too mundane, too nondescript, too familiar.

Even the sense of injustice at the award of the decisive penalty was half-hearted. The visitors had appeared relatively content in a mishmash of a goalless opening until the moment Iasmin Latovlevici found rare space down the left to fling over a fine cross towards Raul Rusescu, looming above Ryan Bertrand at the far post. The full-back, one of a quintet of changes from Saturday's victory over West Bromwich Albion, was panicked by the striker's presence and tugged him down as he sprang to connect, with the Russian official acknowledging the offence.

"It was a soft penalty to give with so many officials around the goal, but, if it was, why no red card? Strange," said Benítez. His opinion was echoed by his opposite number, Laurentiu Reghecampf. Steaua had prevailed against Ajax in the previous round on penalties, so there was no surprise that Rusescu thumped the spot-kick emphatically through Petr Cech's attempt to save, and the visitors were breached. Somewhere amid the vociferous home support, around 500 travelling supporters high up in the gods offered a collective snarl of frustration.

What chances the visitors created thereafter were battered away by Tatarusanu. Arguably the clearest came in the immediate aftermath of Rusescu's reward, Eden Hazard competing for a bouncing ball and, once he had controlled possession and with Steaua defenders complaining about his high boot, exchanging passes expertly with Yossi Benayoun. The Belgian's return liberated his team-mate with a clear sight of goal, only for Benayoun to scuff his shot from the edge of the area, allowing Tatarusanu to save at full stretch. The goalkeeper was not quite as irked by Fernando Torres' volley just before the break, even if the striker chiselled out the opportunity impressively to force a save at the near post. One of these days such an opportunity might actually fly in for him.

Yet this was more of the same for the Spaniard (pictured), all the huff and puff going unrewarded until it gave way to exasperation, his endeavour forever undermined by a heavy touch, an anxious delivery or, quite simply, a poor decision. The game had drifted past the hour when Frank Lampard's deliciously arced diagonal pass fell to him as he edged unopposed into the area. Yet where once he would have cushioned, spun and snapped off a shot at goal, he chose instead to lay the ball off into space at his back. Steaua gratefully scrambled it clear.

The forward's industry remains but his bite is blunt to the tune of one goal in 18 matches. He had been targeted by a fan with a laser during the first half – how he must have wished the local could have used it to direct him towards goal – and his body language had taken on a familiar defeatist look by the end. Chelsea must hope it does not rub off on others.

What positives that could be gleaned centred on Terry's strong performance – the captain will hope he has proved he can feature at Manchester United on Sunday, even if the recent trend is to deny him two outings within a few days – as well as the reality that Steaua did not add further to their lead."We know these ties can be more difficult if you do not score in the away game, so we have to do everything in the home match," added Benítez. "We are disappointed but we still have the belief we can go through. As for Sunday [in the FA Cup], that is another challenge." That will be game 51 of a season that remains trying.